For head units, I always go with Crutchfield. Yes, they aren't the cheapest but (usually) by the time you add in the install kit and wiring harness they usually end up being right on par with other places anyway. You also get install help/advice if you need that sort of thing.

I just got the Pioneer AVIC Z110BT. I checked out a bunch before i decided on it, its definitely the best one out there IMO. I bought it from "dis_sound" on ebay. Not the best price out there, but came recommended by some friends. The z110BT can be bypassed pretty easily. Check it out, I like mine a lot.